Split diffuser

ABSTRACT

A jet pump splitter subassembly is provided having an interior chamber sized to allow a second diffusing cycle while directing the mixed fluid towards at least two exits in the jet pump housing. Preferably each of the exits are spaced uniformly about the periphery of the jet pump.

BACKGROUND

Over the lifetime of a hydrocarbon well the ability to remove the hydrocarbons to the surface diminishes. Therefore, at some point it is necessary to utilize a form of artificial lift to move the hydrocarbons and other fluids from the formation, through the wellbore, and to the surface. One method of lifting the hydrocarbons and other fluids to the surface is to incorporate a jet pump at some point in the fluid column. Jet pumps are particularly well-suited for the corrosive and abrasive conditions in a hydrocarbon well as there are no moving parts in a jet pump.

Jet pumps typically operate by forcing a power fluid through a small opening or nozzle. As the power fluid flows towards into the nozzle its velocity increases thereby causing a drop in pressure as the power fluid exits the nozzle. The nozzle exit is generally known as the venturi. Generally located adjacent to the venturi are side ports which allow the wellbore fluid including the hydrocarbon to mingle with the power fluid as the power fluid exits the nozzle. The drop in pressure of the power fluid at the nozzle exit draws the wellbore fluids into the nozzle area where the power fluid and the wellbore fluid mix. The kinetic energy or momentum of the power fluid due to its now increased velocity is then at least partially transferred to the wellbore fluid increasing the velocity of the wellbore fluid and directing the wellbore fluid into the upper end of a diffuser. As the mixed fluid flows through the diffuser the diffuser opens allowing the velocity of the mixed fluid to decrease causing an increase in the pressure of the fluid. The outflow of the diffuser is then directed into an elbow which in turn directs the mixed fluid to the exterior of the jet pump and then to the surface.

Jet pump efficiency is largely dependent upon feed pressure at the venturi. Therefore, it is desirable to reduce any restrictions within the side ports which are in the intake or suction area of the housing. Generally, the greatest restriction occurs where the intake stream crosses over the discharge stream. Generally, such restriction is reduced by using concentric tubes where the inner tube or discharge has an elbow that directs flow out of one side of the housing. Unfortunately, the inclusion of an elbow increases manufacturing costs and increases the failure rate of the jet pump due to the relative delicacy of the elbow.

SUMMARY

it has been found that it is possible to split the discharge stream into at least two fluid paths. The splitter is generally concentric with the discharge tube and is located below the diffuser. It has been found that rather than forcing the entire flow through the elbow and through one point on the exterior of the housing that by splitting the discharge stream into at least two preferably symmetric fluid paths where each discharge stream exits the pump housing at a relatively symmetric location about the central axis of the pump reduces overall turbulence within the discharge stream prior to exiting the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a side view of a prior art jet pump.

FIG. 2 depicts a side view of a jet pump having a splitter.

FIG. 3 depicts a schematic of the flowpath through a jet pump.

FIG. 4 depicts an orthographic view of the splitter assembly and a portion of the jet pump housing.

FIG. 5 depicts a top view of the splitter assembly in position within the jet pump housing.

DETAILED DESCRIPTION

The description that follows includes exemplary apparatus, methods, techniques, or instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.

FIG. 1 depicts a prior art jet pump where the jet pump 10 is located within casing 12. The jet pump 10 is attached to the lower end of the pump tubing 14. At some point below the jet pump is a packer 16. When the jet pump is run into the well the jet pump 10 is located and the packer 16 is set within the casing 10 at a sufficient depth within the casing 12 to allow wellbore fluids 18 into the lower end of the jet pump 20 and to at least the level of the venturi ports 22. The wellbore fluid 18 then flows through the interior 24 of the jet pump 10 to at least the venturi ports 22. Power fluid 26 is then forced through pump tubing 14 until it reaches jet pump 10 and begins to flow into nozzle 28. Power fluid 26 exits nozzle 28 at venturi chamber 32. Generally, the power fluid 26 exits the nozzle 28 as it reaches its maximum velocity and lowest pressure. The low pressure of power fluid 26 draws wellbore fluid 18 into the venturi chamber 32 where the power fluid 26 mixes with the wellbore fluid 18 causing the wellbore fluid 18 to accelerate. The mixed fluid 34 first enters the mixing chamber 36 and then proceeds into the diffuser 38. In the diffuser 38 the mixed fluid 34 slows but increases in pressure. As the mixed fluid 34 exits the diffuser 38 the mixed fluid 34 enters the elbow 40. The elbow 40 provides a pathway for the mixed fluid 34 to exit the jet pump 10 and enter into the annular area 44 formed between the casing wall 12 and the pump tubing 14 with the jet pump 10. Once the mixed fluid 34 exits the jet pump 10 the pressure induced within the diffuser 38 to the mixed fluid 34 allows the mixed fluid 34 to proceed to the surface as indicated by arrow 46.

However, with the majority of the mixed fluid 34 exiting the jet pump 10 at a single location there is significant turbulence within the mixed fluid and consequent pressure drops within the mixed fluid 34.

FIG. 2 depicts an embodiment of the current invention where the jet pump 110 is located within casing 112. The jet pump 110 is attached to the lower end of the pump tubing 114. At some point below the jet pump is a packer 116. When the jet pump is run into the well the jet pump 110 is located and the packer 116 is set within the casing 110 at a sufficient depth within the casing 112 to allow wellbore fluids 118 into the lower end of the jet pump 120 and to at least the level of the venturi ports 122. The wellbore fluid 118 then flows through the interior 124 of the jet pump 110 to at least the venturi ports 122. Power fluid 126 is then forced through pump tubing 114 until it reaches jet pump 110 and begins to flow into nozzle 128. Power fluid 126 exits nozzle 128 at venturi chamber 132. Generally, the power fluid 126 exits the nozzle 128 as it reaches its maximum velocity and lowest pressure. The low pressure of power fluid 126 draws wellbore fluid 118 into the venturi chamber 132 where the power fluid 126 mixes with the wellbore fluid 118 causing the wellbore fluid 118 to accelerate. The mixed fluid 134 first enters the mixing chamber 136 and then proceeds into the diffuser 138. In the diffuser 138 the mixed fluid 134 slows but increases in pressure. As the mixed fluid 134 exits the diffuser the mixed fluid enters the splitter chamber 150. The splitter chamber 150 has a splitter 152 at the lower end of the splitter chamber 150. The splitter 152 may be a cone or it may be angled surfaces. While the current embodiment of the splitter 152 depicts a flat surface, other shapes may be preferable due to machining constraints, space constraints within the jet pump, or improved fluid flow characteristics. Generally speaking the splitter chamber 150 has at least a first outlet 154 and a second outlet 156. As the mixed fluid 134 enters the splitter chamber 150 the splitter chamber 150 is configured to allow for a second or further expansion of the mixed fluid and consequently a further pressure rise. In certain instances the diffuser 138 and the splitter chamber 150 may be combined into a single unit in turn allowing only a single expansion cycle. The mixed fluid is then directed to the exits through the housing such as first outlet 154 and second outlet 156. The first outlet 154 and the second outlet 156 are configured such that the combined exit area of the outlets is greater than the area of the diffuser exit 160. Mixed fluid then enters the annular area 144 formed by the casing 110 on one side and the pump tubing 114 and the pump 110 on the other side. The packer 116 prevents the mixed fluid from proceeding further down into the well and mixing with the wellbore fluid 118 thereby forcing the mixed fluid 134 to proceed towards the surface.

FIG. 3 depicts fluid flow through a cross-section of the diffuser and splitter of an embodiment of the current invention. Generally, wellbore fluid 201 is located at the inlet 200. The wellbore fluid 201 proceeds upwards through the body of the jet pump as 210 indicated by arrow's 202 and 204. The wellbore fluid 201 continues to proceed upwards in the jet pump until it reaches the venturi chamber, not shown, where the wellbore fluid 201 mixes with the power fluid and is redirected down through the mixing chamber, not shown, and into the diffuser 212 as shown by arrows 214 and 216. The mixed fluid 215 then enters the splitter chamber 220 where due to the larger volume of the splitter chamber 220 the mixed fluid 215 is allowed to undergo a second expansion the splitter 222 then directs the mixed fluid 215 out of the jet pump 210 through ports 256 and 258. It may be observed that passageways 206 and 208 are formed through the body of the jet pump 210 such that the wellbore fluid 201 does not mix with the mixed fluid 209 as the mixed fluid 209 exits the jet pump 210 through ports 256 and 258. In certain stances the flow through the jet pump may be optimized to allow the flow through the venturi, diffuser, and splitter to flow from the lower end of the jet jump towards the surface.

In certain instances, the splitter 222 may be a hard material such as tungsten carbide, it may be a hardened material such as tool steel, or it may have a coating any of which may be added to prolong the life of the splitter in the presence of the direct impingement of solids in the mixed fluid.

FIG. 4 depicts an embodiment of the current invention. In particular FIG. 4 depicts a splitter subassembly 300 and a portion of the jet pump housing 310 prior to having the splitter subassembly 300 placed therein. The splitter subassembly has two ports 354 and 358 that allow fluid access through the splitter mandrel 360. On the exterior of the splitter mandrel 360 is a first splitter wing 362 which extends radially outward from splitter mandrel 360 about the periphery of the first port 354. Additionally, as this particular configuration of splitter has two ports there is a second splitter wing 364 that extends radially outward from splitter mandrel 360 but is offset from the first splitter wing 362 by about 180°. In the event that the splitter required additional ports each port would have a splitter wing and each port and wing would be offset from the other about the same distance about the periphery of the splitter mandrel i.e. for example if there were 3 ports would each be offset from the other by about 120°. At the upper end of the splitter mandrel 360 is an adapter ring 370 the adapter ring 370 is placed so that when the splitter assembly 300 is placed proximate the diffuser in a jet pump the adapter may seal to the diffuser. The seal may be O-rings, a metal to metal seal, welded, soldered, or any other sealing known to the industry. At the lower end of the splitter mandrel 360 is cone 372. Cone 372 is shaped to facilitate wellbore fluid flowing upwards around the diffuser mandrel while minimizing the turbulence in the wellbore fluid as the wellbore fluid flows upwards.

The portion of the jet pump housing 310 depicted has a first port 380 and a second port 382. In practice the diffuser subassembly 300 is lowered into the interior of the jet pump housing 310 such that port 354 of the jet pump subassembly is adjacent to the port 380 of the jet pump housing 310 while port 358 of the jet pump subassembly 300 is adjacent to the port 382 of the jet pump housing 310. The first splitter wing 362 is adjacent to the interior periphery of the jet pump housing 310 port 380 while the second splitter ring 364 is adjacent to the interior periphery of the jet pump housing 310 port 382. Each of the splitter wings 362 and 364 are sealed to the jet pump housing 310 by O-rings, metal to metal seals, welding, soldering, or any other sealing known to the industry. When an operation wellbore fluid will flow upwards around splitter mandrel 360 and around each of the wings 362 and 364 and will be isolated by the seals from the mixed fluid flowing downward through the interior of splitter mandrel 360 out through ports 354 and 358 and ultimately flowing outwards through port 380 and 382 of the jet pump housing 310.

The interior pathways may be more readily visualized in FIG. 5 where the wellbore fluid proceeds upward through the annular area 390 formed by the jet pump housing 310 and the splitter mandrel 360 while mixed fluid moves downward through the interior 392 of the jet pump mandrel 360 the mixed fluid then proceeds through ports 354 and 358 of the splitter mandrel then through the interior of wings 362 and 364 and then through ports 380 and 382 of the jet pump housing 310 as indicated by arrow 396.

The methods and materials described as being used in a particular embodiment may be used in any other embodiment. While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible.

Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter. 

What is claimed is:
 1. A jet pump comprising: a housing, a power fluid, a wellbore fluid, a mixing chamber, wherein the power fluid and the wellbore fluid combine into a mixed fluid. an expansion chamber, a splitter, wherein the splitter forms the mixed fluid into at least a first and second stream.
 2. The jet pump of claim 1 wherein, the splitter forms the mixed fluid into at least two approximately symmetric streams.
 3. The jet pump of claim 1 wherein, the at least first and second streams are directed towards at least two ports in an exterior of the housing.
 4. The jet pump of claim 1 wherein, the at least first and second streams are directed towards at least two ports wherein each port has a wing.
 5. The jet pump of claim 1 wherein, the splitter is a cone.
 6. The jet pump of claim 1 wherein, the splitter is in a splitter chamber, wherein the splitter chamber allows further expansion of the mixed fluid.
 7. The jet pump of claim 7 wherein, the splitter is optimized to reduce turbulence within the splitter chamber.
 8. A method of forming a jet pump splitter assembly comprising: placing a splitter within a tubular, forming at least a first and second port within the tubular, wherein the at least first and second ports are each located in a wall of the tubular above the splitter, providing an adaptor to provide a flow path for a mixed fluid between a venture and the splitter.
 9. The method of forming a jet pump splitter assembly of claim 8 wherein, the at least first and second ports are symmetric about the axis of the jet pump.
 10. The method of forming a jet pump splitter assembly of claim 8 wherein, the splitter forms the mixed fluid into about symmetric streams.
 11. The method of forming a jet pump splitter assembly of claim 8 further comprising a splitter chamber.
 12. The method of forming a jet pump splitter assembly of claim 8 wherein, the splitter chamber allows for expansion of the mixed fluid.
 13. The method of forming a jet pump splitter assembly of claim 8 wherein, the splitter is optimized to reduce turbulence within the mixed fluid streams.
 14. A jet pump comprising: a housing, a power fluid, a wellbore fluid, a venturi, wherein the power fluid mixes with the wellbore fluid to form a mixed fluid. a first expansion chamber, a second expansion chamber, at least two ports allowing a mixed fluid to exit the second expansion chamber.
 15. The jet pump of claim 14 wherein, a splitter is located within the second expansion chamber.
 16. The jet pump of claim 15 wherein, the splitter forms the mixed fluid into at least two approximately symmetric streams.
 17. The jet pump of claim 15 wherein, the splitter is a cone.
 18. The jet pump of claim 15 wherein, the splitter is optimized to reduce turbulence within the second expansion chamber.
 19. The jet pump of claim 16 wherein, the at least two approximately symmetric streams are directed towards the at least two ports in an exterior of the housing.
 20. The jet pump of claim 16 wherein, the at least two approximately symmetric streams are directed towards at least two ports wherein each port has a wing. 